65 PRODUCTION OF PORCINE NUCLEAR TRANSFER EMBRYOS USING FETAL FIBROBLAST CELLS ANALYZED ON APOPTOSIS
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Notice bibliographique
Résumé
One of the most important factors that determine the developmental potential of mammalian cloned embryos is the structuro-functional quality of nuclear donor cells. Biochemical changes that are some of the earliest symptoms of apoptosis signal transduction are not reflected in the morphological features of somatic cells. Therefore, an appropriate system of cell selection would enable the sorting of donor nuclei with high morphological and biochemical susceptibility to somatic cloning. The aim of our study was to examine the in vitro developmental competencies of porcine nuclear transfer (NT) embryos reconstructed with fetal fibroblast cells that had been analyzed for apoptosis by live-fluorescent labelling. Frozen/thawed fetal fibroblast cells, which had been in vitro-cultured to a confluent state, were used for analysis. To detect the early apoptotic changes in the fibroblast cells, a single cell suspension of nuclear donor cells was subjected to dyeing with live-DNA green fluorochrome YO-PRO-1. The recipient cells were in vitro-matured oocytes. Maternal chromosomes were removed by a chemically assisted microsurgical technique. Then, single nuclear donor cells were inserted into the perivitelline space of enucleated oocytes. Fibroblast cell-ooplast couplets were simultaneously fused and activated with two consecutive DC pulses of 1.2 kV/cm for 60 µs. Reconstructed embryos were in vitro cultured in 50-µL drops of NCSU-23 medium supplemented with 0.4% BSA-V for 6 to 7 days at 38.5°C in a humidified atmosphere of 5% CO2 and 95% air. The rates of cleavage and development to morula/blastocyst stages were examined on Days 2 and 6/7, respectively. After fluorescent analysis of approximately 50 different random samples collected from the population of fetal fibroblast cells, that had been labelled with YO-PRO-1 dye, it was found that a relatively high proportion of donor cells revealed ultrastructural apoptotic changes. The percentage of late apoptotic cells with advanced morphological transformations was about 40% of the total pool of the fibroblast cells. A total of 262/270 (97.0%) enucleated oocytes were subjected to reconstruction and 141/262 (53.8%) were successfully fused with non-apoptotic nuclear donor cells. Following the simultaneous fusion/activation protocol, reconstituted oocytes were selected for in vitro culture. Out of 262, 133 (50.8%) cultured NT embryos cleaved. The frequencies of cloned embryos that reached the morula and blastocyst stages were 48/133 (36.0%) and 10/133 (7.5%), respectively. In conclusion, morphology is a sufficient selection factor for detection of apoptosis in the cultured (confluent) fetal fibroblast cells to be used for cloning. Moreover, it was found that YO-PRO-1 fluorochrome may be not able to detect the early phases of apoptosis, because only the morphologically abnormal cells emitted the YO-PRO-1-derived fluorescence. This research was supported by the State Committee for Scientific Research as a Solicited Project number PBZ-KBN-084/P06/2002/4.2 from years 2003 to 2005.
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Prédiction distillée sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Apprise à partir de 10 348 étiquettes directes de Codex et de 10 348 étiquettes directes de Gemma. Le mode candidate est l'union des têtes enseignantes seuillées; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont ni des étiquettes humaines ni des étiquettes directes de modèles de pointe.
Scores Codex et Gemma par catégorie
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,001 | 0,000 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,001 | 0,000 |
| Bibliométrie | 0,000 | 0,000 |
| Études des sciences et des technologies | 0,000 | 0,000 |
| Communication savante | 0,000 | 0,000 |
| Science ouverte | 0,000 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,000 | 0,000 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découle